Achiral phenolic N-oxides as additives: an alternative strategy for asymmetric cyanosilylation of ketones

The activation of chiral titanium(IV) complexes with additives, phenolic N-oxides, is found to provide an alternative strategy for asymmetric cyanosilylation of ketones in excellent yield With LIP to 82%, ee. (C) 2004 Elsevier Ltd. All rights reserved

INFLUENCE OF LINEAR ALKYLBENZENE SULFONATE (LAS) AS ORGANIC COSOLVENT ON LEACHING BEHAVIOR OF PCDD/FS FROM FLY-ASH AND SOIL

The leaching of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was measured in soil and standard fly ash column eluted with pure water and linear alkylbenzene sulfonate (LAS)- water. The data obtained were used to evaluate the leachability of PCDD/Fs from waste dump like incineration residual slag and fly ash deposition. The leaching rate was shown to be increased significantly by using LAS water. The leachate contents of PCDD/Fs were above their known water solubility. Concentration of PCDD/Fs in the leachates as well as the relative leaching (calculated on the fly ash content) increased with increasing chlorinating degree and decreasing water solubility. LAS above the critical micelle concentration (CMC) probably enhances PCDD/Fs solubility

Software for the frontiers of quantum chemistry : An overview of developments in the Q-Chem 5 package

This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange–correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear–electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an “open teamware” model and an increasingly modular design.This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange-correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear-electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an "open teamware" model and an increasingly modular design.Peer reviewe

New Developments in Charge Transfer Multiplet Calculations: Projection Operations, Mixed-Spin States and pi-Bonding

This paper presents a number of new additions to the charge transfer multiplet calculations as used in the calculation of L edge X-ray absorption spectra of 3d and 4d transition metal systems, both oxides and coordination compounds. The focus of the paper is on the consequences of the optimized spectral simulations for the ground state, where we make use of a recently developed projection technique. This method is also used to develop the concept of a mixed-spin ground state, i.e. a state that is a mixture of a high-spin and low-spin state due to spin-orbit coupling combined with strong covalency. The charge transfer mechanism to describe {pi}-bonding uses the mixing of the metal-to-ligand charge transfer (MLCT) channel in addition to the normal CT channel and allows for the accurate simulation of {pi}-bonding systems, for example cyanides

A Surface Energy Transfer Nanoruler for Measuring Binding Site Distances on Live Cell Surfaces

Measuring distances at molecular length scales in living systems is a significant challenge. Methods like Forster resonance energy transfer (FRET) have limitations due to short detection distances and strict oriental ions. Recently, surface energy transfer (SET) has been used in bulk solutions; however, it cannot be applied to living systems. Here, we have developed an SET nanoruler, using aptamer-gold nanoparticle conjugates with different diameters, to monitor the distance between binding sites of a receptor on living cells. The nanoruler can measure separation distances well beyond the detection limit of FRET. Thus, for the firs: time, we have developed an effective SET nanoruler for live cells with long distance, easy construction, fast detection, and low background. This is also the first time that the distance between the aptamer and antibody binding sites in the membrane protein PTK7 was measured accurately. The SET nanoruler represents the next leap forward to monitor structural components within living cell membranes.Chinese Government ; Academic Women Madelyn Lockhart Dissertation Fellowship ; NIH ; NSF ; National Basic Research Program of China [2007CB935603, 2010CB732402]; [2009ZX10004-312

Sulfur K-Edge XAS and DFT Calculations on [Fe4S4]2+Clusters: Effects of H-bonding and Structural Distortion on Covalency and SpinTopology

Sulfur K-edge X-ray absorption spectroscopy of a hydrogen-bonded elongated [Fe{sub 4}S{sub 4}]{sup 2+} cube is reported. The data show that this synthetic cube is less covalent than a normal compressed cube with no hydrogen bonding. DFT calculations reveal that the observed difference in electronic structure has significant contributions from both the cluster distortion and from hydrogen bonding. The elongated and compressed Fe{sub 4}S{sub 4} structures are found to have different spin topologies (i.e., orientation of the delocalized Fe{sub 2}S{sub 2} subclusters which are antiferromagnetically coupled to each other). It is suggested that the H-bonding interaction with the counterion does not contribute to the cluster elongation. A magneto-structural correlation is developed for the Fe{sub 4}S{sub 4} cube that is used to identify the redoxactive Fe{sub 2}S{sub 2} subclusters in active sites of HiPIP and ferredoxin proteins involving these clusters

Synthesis of thick Ni66Cr5Mo4Zr6P15B4 amorphous alloy coating and large glass-forming ability by laser cladding

A thick amorphous alloy (a-alloy) coating was synthesized by laser cladding. The a-alloy had a multicomponent chemistry, i.e., Ni66Cr5MO4Zr6P15B4 (in atom%). The maximum thickness of the coating is 0.8 mm. The a-alloy coating had large glass-forming ability (GFA) with wide supercooled liquid region (SLR) ranging from 52 to 61 K through the coating. The reason for high GFA in the a-alloy coating was discussed. (C) 2002 Published by Elsevier Science B.V

In-Plane Deformation Mechanics for Highly Stretchable Electronics

Scissoring in thick bars suppresses buckling behavior in serpentine traces that have thicknesses greater than their widths, as detailed in a systematic set of analytical and experimental studies. Scissoring in thick copper traces enables elastic stretchability as large as approximate to 350%, corresponding to a sixfold improvement over previously reported values for thin geometries (approximate to 60%).</p

Technical Challenges for the Head-on Collisions and Extraction at the ILC

An interaction region with head-on collisions is considered as an alternative to the baseline ILC configuration. Progress in the final focus optics design includes engineered large bore superconducting final doublet magnets and their 3D magnetic integration in the detector solenoids. Progress on the beam separation optics is based on technical designs of electrostatic separator and special extraction quadrupoles. The spent beam extraction is realized by a staged collimation scheme relying on realistic collimators